Balloon catheter

ABSTRACT

Provided is a new balloon catheter enabling formation of, with high dimensional accuracy and excellent shape adaptability with respect to a balloon, an additional structure such as a blade and/or a reinforcement member on the balloon. The balloon catheter includes a shaft and an expandable/contractible balloon on the distal end side of the shaft, with an additional structure having a prescribed pattern being formed through electroforming or the like directly onto an inner circumferential surface and/or an outer circumferential surface of the balloon.

TECHNICAL FIELD

The present invention relates to a balloon catheter that is a medicalinstrument including a balloon provided on a distal end side of a shaftwhich is used for various treatments such as percutaneous angioplastyand stent operation by being inserted in a somatic lumen like a bloodvessel.

BACKGROUND ART

A balloon catheter has been known as one medical instrument fortransdermally curing a lesion location in a lumen like a blood vessel.As is disclosed in Japanese Unexamined Patent Publication No.JP-A-H05-084304 (Patent Document 1), Japanese Domestic Publication ofInternational Patent Application No. JP-A-2008-509749 (Patent Document2), Japanese Domestic Publication of International Patent ApplicationNo. JP-A-2008-519654 (Patent Document 3), and the like, for the ballooncatheter, a balloon is provided on a distal end side of a shaft thatshould be inserted in the lumen from the outside of a body. The balloonis expandable and contractible by supply and discharge operation of apressurized fluid at a proximal end side of the shaft positioned outsidethe body. This balloon catheter enables some cures e.g., expansion of astenosis portion of the blood vessel using the balloon, stent deliveringand indwelling in relation to the expanded stenosis portion, andslitting in a calcified portion with a blade arranged on the outercircumference of the balloon.

The required characteristics for the balloon of the balloon catheterdiffer depending on specific purposes etc. For example, when a greatforce is required in order to expand the lumen, the wall of the balloonneeds great pressure resistance. For slitting in the calcified portionof the blood vessel, it is necessary to provide a blade of high rigidityon the outer circumference of the balloon.

For responding to these requests, it is conceivable that the pressureresistance is improved by material change or thickening of the balloon,or that a blade part in a projection shape is integrally formed on theouter circumference by shape change of the balloon, for example.

However, by improving the pressure resistance through material change orthickening of the balloon, or by forming the blade part through shapechange of the balloon, or the like, the required characteristics may bedifficult to sufficiently attain. For example, the balloon may be sothickened and thus hardened for realizing the required pressureresistance as to deteriorate crossability through the lesion locationetc.

Japanese Domestic Publication of International Patent Application No.JP-A-2009-513299 (Patent Document 4) discloses a structure of theballoon catheter wherein a resin-reinforced tube having holes pierced onthe circumference wall thereof is inserted in the balloon forreinforcement. However, this balloon catheter is difficult tomanufacture, because the manufacture needs not only a mold and specialfacilities for forming the resin-reinforced tube independently from theballoon, but also precise dimension matching of the balloon and theresin-reinforced tube. Since the resin-reinforced tube must be piercedon the circumference wall of the tube body, the degree of freedom forshape is small, so that it is also difficult to highly achieve variouscharacteristics as required for the balloon catheter.

BACKGROUND ART DOCUMENT Patent Document

Patent Document 1: JP-A-H05-084304

Patent Document 2: JP-A-2008-509749

Patent Document 3: JP-A-2008-519654

Patent Document 4: JP-A-2009-513299

SUMMARY OF THE INVENTION Problem the Invention Attempts to Solve

The present invention was made against the background described above,and the problem to be solved is to provide a balloon catheter with anovel structure capable of highly meeting various requests depending onthe purposes with a great degree of freedom.

Means for Solving the Problem

A first mode of the present invention provides a balloon catheterincluding a balloon provided on a distal end side of a shaft,characterized in that: an additional structure having a prescribedpattern is provided on a surface of at least one of an innercircumferential surface and an outer circumferential surface of theballoon by being directly formed thereon.

In the balloon catheter of the structure according to this mode, theadditional structure is directly formed on the surface of the balloon,whereby it is possible to provide the additional structure preciselycorresponding to the balloon shape. The shape of the additionalstructure can be set on the surface of the balloon with a great degreeof freedom, without limitation to the tube shape like the conventionalstructure disclosed in Patent Document 4. Therefore, it becomes alsopossible to advantageously realize the required characteristics for theballoon catheter.

A second mode of the present invention provides the balloon catheteraccording to the first mode, wherein the additional structure is formedon the inner circumferential surface of the balloon.

In the balloon catheter of the structure according to this mode, theadditional structure is directly formed on the inner circumferentialsurface of the balloon. This makes it possible to form so-called highpressure resistant balloon with improved pressure resistanceperformance, e.g., of about 24 atm for coronary artery, while preventingdirect contact of the additional structure with a body tissue like ablood vessel. In the balloon catheter of the structure according to thismode, even if the additional structure falls off the balloon, theadditional structure will stay inside the catheter, with no risk ofdamaging the vessel wall.

A third mode of the present invention provides the balloon catheteraccording to the first or second mode, wherein the additional structureis formed by at least one of thermal spraying and vacuum deposition.

A fourth mode of the present invention provides the balloon catheteraccording to the first or second mode, wherein the additional structureis formed by at least one of electroforming and etching.

In the balloon catheter of the structure according to the third orfourth mode of the present invention, by using such arts aselectroforming, it is possible to form the additional structure with ahigher dimension accuracy for shape and thickness.

A fifth mode of the present invention provides the balloon catheteraccording to any of the first to fourth modes, wherein the additionalstructure has a tubular mesh shape that is continuous in acircumferential direction of the balloon.

In the balloon catheter of the structure according to this mode, byadopting the mesh shape of additional structure, it is possible topermit deformation of the balloon, and keep good softness, and reinforcethe circumference wall of the balloon, thereby improving the pressureresistance performance. The mesh shape of this mode involves variousembodiments wherein linear bodies connect or intersect to provide anopening. For example, it is possible to use a structure having aplurality of spiral linear bodies intersecting one another, astent-formed structure having linear bodies that extend in thecircumferential direction while meandering in a wave shape or alightning shape which are partially connected in the axial direction,and the like.

Note that it is possible as well to adopt the mesh-shaped additionalstructure according to the present mode, in addition to a differentadditional structure of another mode that is formed on the innercircumferential surface or the outer circumferential surface of theballoon according to a sixth mode etc. as will be described later.

A sixth mode of the present invention provides the balloon catheteraccording to any of the first to fifth modes, wherein the additionalstructure has a linear shape that is continuous in a lengthwisedirection of the balloon.

In the balloon catheter of the structure according to this mode, it ispossible to have the additional structure project on the outercircumferential surface of the balloon so as to constitute a blade. Thisblade constituted by the additional structure may be formed of a rigidmaterial like a metal which is different from that of the balloon and itcan be preferably used as a cutting balloon catheter or the like. Forthe balloon catheter of the structure according to this mode, it is alsopossible to make the additional structure project on the innercircumferential surface of the balloon, and it becomes easy to formso-called high pressure resistant balloon with improved pressureresistance performance, e.g., of about 24 atm for coronary artery.

A seventh mode of the present invention provides the balloon catheteraccording to any of the first to sixth modes, wherein the additionalstructure is deformable due to expansion and contraction of the balloon.

In the balloon catheter of the structure according to this mode, undereither expanding or contracting state of the balloon, such action asreinforcement for the balloon can be more effectively kept andexhibited. For permitting the deformation of the additional structure,the additional structure itself can be formed of a material that canundergo deformation like extension and contraction. Alternatively, theadditional structure can have a curved shape so as to be a structureallowed to undergo deformation like extension and contraction.

An eighth mode of the present invention provides the balloon catheteraccording to any of the first to seventh modes, wherein the additionalstructure is secured on the surface of the balloon.

In the balloon catheter of the structure according to this mode, theadditional structure is secured on the balloon, thereby enablingprevention of damages on the additional structure, as well asimprovement in reinforcing effect for the balloon, for example.Especially in the present invention, the additional structure is formeddirectly on the inner circumferential surface or the outercircumferential surface of the balloon. This makes it easier to readilyand firmly realize the attachment structure of the additional structureto the balloon, by comparison with a case of separate formation andlater attachment.

Effect of the Invention

According to the present invention, in the balloon catheter, theadditional structure precisely corresponding to the balloon shape can beprovided with a great degree of freedom under no limitation to the tubeshape etc. This additional structure can meet various characteristicsrequired for the balloon catheter, e.g., pressure resistance performanceand strength of the balloon, setting of the blade with respect to theouter circumferential side of the balloon.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a general view suitable for explaining an outline structure ofa balloon catheter as a first embodiment of the present invention.

FIG. 2 is a longitudinal cross sectional view showing a distal end sideof the balloon catheter shown in FIG. 1 when the balloon is expanded, assuitable for explaining a mode of an additional structure in theballoon.

FIG. 3 is a cross sectional view taken along line 3-3 of FIG. 2.

FIG. 4 is an outside view showing the distal end side of the ballooncatheter as another embodiment of the present invention when the balloonis expanded, as suitable for explaining another mode of the additionalstructure.

FIG. 5 is a cross sectional view taken along line 5-5 of FIG. 4.

EMBODIMENTS FOR CARRYING OUT THE INVENTION

The embodiment of the present invention will be described below inreference to the drawings.

First, FIG. 1 shows a balloon catheter 10 as a first embodiment of thepresent invention. This balloon catheter 10 has a long catheter 12,wherein a balloon 14 is provided on the distal end side of the catheter12 (the left side in FIG. 1), while a hub 16 is provided on the proximalend side of the catheter 12 (the right side in FIG. 1). The distal endside of the catheter 12 is inserted into a blood vessel through a partof a human body such as a wrist or a thigh until it reaches a treatmentlocation like a coronary artery, and then, the balloon 14 is swollen. Byso doing, it is possible to perform a treatment of expanding thestenosis portion in the blood vessel to recover normal blood flow, andthe like.

More specifically, as FIG. 2 shows, the catheter 12 has a structureincluding double tubes wherein a tubular internal shaft 18 is insertedin a tubular external shaft 20.

Both the internal shaft 18 and the external shaft 20 can be formed withvarious materials and structures known conventionally as ones havingcharacteristics with which they can be curved along the blood vessel.Specifically, each shaft can be formed of a synthetic resin materialsuch as polyamide, vinyl chloride, polyurethane, polyimide,polyethylene, polyester elastomer, polypropylene,polytetrafluoroethylene, polyetheretherketone, polyvinylidene fluoride,a metallic material such as stainless steel, nickel-titanium alloy, anda combination of them.

The distal end part of the internal shaft 18 protrudes from the distalend of the external shaft 20 by a prescribed length. At the protrudingend part of the internal shaft 18, a distal end tip 22 is attached. Thedistal end tip 22 is preferably softer than the internal shaft 18. Forthe distal end tip 22, the outer peripheral face has a tapered shapewhose diameter gets gradually smaller as it goes toward the distal endside, and a central hole that communicates with the lumen of theinternal shaft 18 is formed by piercing on the central axis thereof.

On the distal end part of the internal shaft 18 protruding from theexternal shaft 20, imaging markers 24, 24 are fixed. The imaging marker24 is a member formed of a metallic material with radiopacity like aplatinum-iridium alloy in an annular shape or a C character shape, andis fixed on the circumference wall of the internal shaft 18.

About the distal end part of the internal shaft 18 protruding from theexternal shaft 20, the balloon 14 is externally disposed. The balloon 14is constituted by a tubular body formed by a film of a deformablesynthetic resin material etc., for example, and the balloon 14 canundergo expanding/contracting deformation in the radial direction.

As the material of the balloon 14, materials known conventionally can beadopted. For example, polyethylene terephthalate, nylon, polyamide,polyether amide, polyether block amide copolymer, polyethylene,polyethylene elastomer, polypropylene, silicone rubber, latex rubber,and the like are preferably used.

When the balloon 14 of this embodiment expands, the balloon 14 takes aform wherein the axially middle part thereof is substantially acylinder, while tapered tubes whose diameters get gradually smaller asthey go to their respective outsides integrally extend out from the bothaxial ends of the axially middle part. When the balloon 14 contracts,the balloon 14 may collapse in an irregular fashion so as to reduce thediameter of its circumference wall. Alternatively, in the contraction,the balloon 14 can be set with a prescribed folded shape such that theballoon 14 is wrapped in the circumferential direction as folded at aplurality of locations on the circumference like an umbrella.

Both axial ends of the balloon 14 are fluidtightly fixed respectively onthe outer peripheral face of the distal end side of the external shaft20 and the outer peripheral face of the distal end side of the internalshaft 18, at the small-diameter side ends of the both tapered tubes.Thus, the balloon 14 defines an inside space on the outer peripheralface of the distal end side of the internal shaft 18, as tightly closedfrom the outside. In the space formed inside the balloon 14, theinternal shaft 18 is disposed to pass through in the axial direction,while, inside the external shaft 20, a space formed on the outerperipheral face of the internal shaft 18 opens to be in communication.

Note that the balloon catheter 10 of this embodiment is a rapid exchangetype. Specifically, the external shaft 20 has a structure wherein adistal shaft 26 and a proximal shaft 28 are connected to each other inthe axial direction. The proximal end part of the internal shaft 18inserted in the distal shaft 26 opens on the outer peripheral face ofthe connection section between the distal shaft 26 and the proximalshaft 28 or its proximity, at the middle portion in the lengthwisedirection of the external shaft 20.

The inner lumen of the internal shaft 18 constitutes a guide wire lumen30 for guide wire insertion. This guide wire lumen 30 extends from thedistal end to the middle part of the catheter 12. That is, one end ofthe guide wire lumen 30 opens at the distal end of the catheter 12through the distal end tip 22, while the other end opens on the outerperipheral face of the external shaft 20 at the middle part in thelengthwise direction thereof

The inner lumen of the external shaft 20 constitutes a pressureregulating lumen 32 on the outer peripheral face of the internal shaft18. This pressure regulating lumen 32 extends across about the wholelength of the catheter 12. That is, the pressure regulating lumen 32opens at the proximal end side of the proximal shaft 28 via the hub 16,and extends in the distal shaft 26 on the outer peripheral side of theinternal shaft 18 with an annular cross section, and opens on the distalend face of the distal shaft 26 to communicate with the inside of theballoon 14.

Here, as FIGS. 2 and 3 show, an additional structure 36 is provided onan inner circumferential surface 34 of the balloon 14. For theadditional structure 36 of this embodiment, the inner circumferentialsurface 34 of the balloon 14 is one formation surface, and it isdirectly formed on the inner circumferential surface 34. This allows theadditional structure 36 to have a tubular mesh shape that is asubstantially braid form as a whole, including two intersecting groupsof spiral linear bodies, which are inclined to the opposite sides toeach other relative to the circumferential direction. Specifically, theadditional structure 36 of this embodiment is a tubular body that iscontinuous in the circumferential direction and the axial direction as awhole, by the plurality of linear bodies extending in the axialdirection while slanting with a prescribed angle relative to thecircumferential direction.

According to the additional structure 36 of this mesh shape, bydeformation of each linear body, expanding/contracting deformation canbe advantageously allowed. Therefore, although the additional structure36 remains secured on the inner circumferential surface of the balloon14, the expanding/contracting deformation of the balloon 14 ispermitted.

In the present embodiment, across almost all of the innercircumferential surface 34 of the balloon 14, the mesh-shaped additionalstructure 36 is disposed. However, the disposition location, the size ofthe disposition area, and the like for the additional structure 36 arenot limited. For example, the additional structure 36 can be disposedonly in the tubular axially central part of the balloon 14 for whichpressure deformation tends to become large in expansion of the balloon14.

For this additional structure 36, the diameter of each linear body, themesh size, and the like can be adjusted as appropriate depending on therequired characteristics for the balloon catheter 10, under nolimitation. In the same way, the material of the additional structure 36can be selected, and ceramics, synthetic resins and the like can beadopted.

Preferably, the additional structure 36 formed of a metal-based materialby electroforming, etching, thermal spraying, vacuum deposition, or thelike is adopted. Alternatively, the additional structure 36 formed of aresin-based material by thermal spraying, vacuum deposition, or the likeis used.

By forming the additional structure 36 directly on the innercircumferential surface 34 of the balloon 14, the additional structure36 can be secured to the balloon 14 with some force. For example, byproviding a resin layer or an adhesive layer as suitable on the innercircumferential surface 34 of the balloon 14 in advance, it is possiblethat the additional structure 36 is not adhered to the innercircumferential surface 34 of the balloon 14, or that the additionalstructure 36 is more securely adhered thereto. Moreover, it is alsopossible to mix a curable metal paste layer that forms the additionalstructure 36 through thermal spraying, vacuum deposition, or the like,with a resin material that exhibits a fixation force in relation to theballoon 14, thereby improving the fixation force of the additionalstructure 36 to the balloon 14.

In the balloon catheter 10 of the present embodiment wherein theabove-described additional structure 36 is provided on the innercircumferential surface of the balloon 14, by being formed on thesurface of the balloon 14, the additional structure 36 whose shapeprecisely corresponds to the shape of the balloon 14 can be stablyprovided. This makes it possible to effectively and stably exert theimprovement effect of the pressure resistance and the strength for theballoon 14 by the additional structure 36.

The additional structure 36 is formed by electroforming, etching, or thelike, so that it can be provided with free setting for the shape, thedimension, and the disposition location, without limitation to thetubular shape like the conventional structure. Besides, since a highdimension accuracy can be obtained, the performance can be stablyattained, whereby the target performance like improvement in thepressure resistance, the strength, the durability and the like inrelation to the balloon 14 is favorably exhibited.

The network structure, the spiral structure or the like shown in theaforesaid embodiment is formed with the intersection structure of linearbodies with a width thin enough, so that it is also possible to get softdeformation performance of the additional structure 36. Thus, insertioneasiness of the balloon catheter in relation to the blood vessel can bekept well without considerably hampering the expanding/contractingdeformation of the balloon.

In this embodiment, the additional structure 36 is formed on the innercircumferential surface of the balloon 14. Thus, the balloon catheter 10has the structure wherein the additional structure 36 is covered by theballoon 14, thereby preventing direct contact of the additionalstructure 36 with body tissues like the blood vessels, and hence theresultant problems. This leads to another advantage of securing a greatdegree of freedom in selection for the material, the shape, and the likeof the additional structure 36.

The embodiment of the present invention has been described above, butthis invention is not interpreted in a limited way by the specificdescription in the above-mentioned embodiment etc. In the presentinvention, for forming the additional structure, some of various artsincluding electroforming, etching, thermal spraying, and vacuumdeposition can be used in combination, for example. Besides, byutilizing these film production techniques, the additional structure maybe formed with a layered structure of different materials by performinga plurality of electroforming works, or the like.

As the specific shape of the additional structure, the linear bodyhaving the above-described linear shape that is continuous in thelengthwise direction of the balloon, the tubular body having a spirallinear shape like a coil spring, or the tubular body of the networkstructure including two intersecting groups of plural spiral linearshapes, which are inclined to opposite sides to each other relative tothe circumferential direction, wherein the two groups are integrallylinked at the intersection parts (see FIG. 2) is used. Besides, it isalso possible to adopt the additional structure formed on the basis of acurved linear shape extending in the circumferential direction with arepetitive wave form, for example.

In the aforementioned embodiment, the additional structure 36 isprovided on the inner circumferential surface of the balloon 14, but itcan be formed on the outer circumferential surface of the balloon 14,instead of or in addition to the inner circumferential surface of theballoon 14. By forming the additional structure 36 on the outercircumferential surface of the balloon 14, the expanding deformation ofthe balloon 14 acts to a direction such that the expansion pushes theballoon 14 on the additional structure. Therefore, the improvementeffect for the pressure resistance performance of the balloon by theadditional structure is even more effectively exhibited, while thesecured state of the additional structure in relation to the balloon canbe more stably retained.

It is possible to perform cooling treatment of the balloon 14 asappropriate when forming the additional structure on the surface of theballoon 14, considering the adopted forming method, material, and thelike. This cooling treatment can be, for example, cooling control of theatmosphere temperature. Alternatively, it is possible to have a coolingfluid that flows by circulation or convection flow in contact with theouter circumferential surface or the inner circumferential surface ofthe balloon 14 on the side opposite to the formation surface of theadditional structure for cooling.

As the additional structure, other than the above-mentioned meshstructure and spiral structure, it is also possible to use a linear bodyextending independently, as parallel to the axial direction or asinclined by a prescribed angle. In this case, a single linear body or aplurality of linear bodies may be disposed on the inner circumferentialsurface or the outer circumferential surface of the balloon 14.

Specifically, for example as FIG. 4 shows, it is possible to provideadditional structures 80 comprising linear bodies that extend linearlyas parallel to the axial direction on the outer circumferential surfaceof the balloon 14. As FIG. 5 shows, these additional structures 80 areformed to project on an outer circumferential surface 82 of the balloon14, thereby constituting blades. Note that the additional structures 80can be formed directly on the outer circumferential surface 82 of theballoon 14 by electroforming etc., as well as the above-citedembodiment.

In the embodiment shown in FIGS. 4 and 5, the additional structures 80can be provided as the blades projecting on the outer circumferentialsurface of the balloon 14. Owing to these additional structures 80, thereinforcement effect of the balloon 14 can be attained, while theballoon 14 can be constituted as a cutting balloon. Each additionalstructure 80, which extends in the axial direction, may be inclined onlyby a prescribed angle with respect to the circumferential direction, andit may have convex and concave portions like a saw blade in itsprojecting tip. Additionally, it is possible as well to provide aring-shaped connection part that extends in the circumferentialdirection to connect the plurality of additional structures 80 with oneanother.

The additional structure with the prescribed pattern that may be variousshapes including mesh shape and linear shape can be formed on either orboth of the outer circumferential surface and the inner circumferentialsurface of the balloon.

Adopted in the above-mentioned embodiment is a rapid exchange type ofcatheter wherein the proximal end side of the guide wire lumen 30 openson the outer circumferential surface of the catheter 12. Alternatively,it is possible to use an over-the-wire type of catheter wherein theproximal end side of the guide wire lumen opens to the outside via thehub 16 provided at the proximal end side of the external shaft 20.

In addition to them all, other embodiments including various changes,amendments, modifications and the like on the basis of the knowledge ofthe skilled person, which are not recited one by one, can be used torealize the present invention. Needless to say, as long as theseembodiments do not deviate from the concept of this invention, they areall included in the range of the present invention.

KEYS TO SYMBOLS

10: Balloon catheter; 12: Catheter; 14: Balloon; 16: Hub; 18: Internalshaft; 20: External shaft; 22: Distal end tip; 34: Inner circumferentialsurface; 36, 80: Additional structure; 82: Outer circumferential surface

1. A balloon catheter comprising: a shaft including a distal end side; aballoon provided on the distal end side of the shaft and including aninner circumferential surface and an outer circumferential surface; andan additional structure having a prescribed pattern that is provided onat least one of the inner circumferential surface and the outercircumferential surface of the balloon by being directly formed thereon.2. The balloon catheter according to claim 1, wherein the additionalstructure is formed on the inner circumferential surface of the balloon.3. The balloon catheter according to claim 1, wherein the additionalstructure is formed by at least one of thermal spraying and vacuumdeposition.
 4. The balloon catheter according to claim 1, wherein theadditional structure is formed by at least one of electroforming andetching.
 5. The balloon catheter according to claim 1, wherein theadditional structure has a tubular mesh shape that is continuous in acircumferential direction of the balloon.
 6. The balloon catheteraccording to claim 1, wherein the additional structure has a linearshape that is continuous in a lengthwise direction of the balloon. 7.The balloon catheter according to claim 1, wherein the additionalstructure is deformable due to expansion and contraction of the balloon.8. The balloon catheter according to claim 1, wherein the additionalstructure is secured on the surface of the balloon.